The invention relates to a method and device for manipulating homogeny, taste, flavor, body, composition and visual appearance of beverages, including accelerating wine aging and maturation of beer and liquors. More particularly, the invention relates to a short-time exposure of beverage to increased pressure, heat and vigorous mixing via flow-through hydrodynamic cavitation to achieve desirable chemical and/or physical changes in the beverage. In a matter of seconds the inventive method and device produces wines with a prolonged shelf life and taste similar to those of wines subjected to years of conventional oak barrel-aging.
Wine is an alcoholic beverage made from the pulp, juice and/or skin of grapes by fermentation, wherein yeast converts the sugars contained in the grapes to ethyl alcohol (ethanol or alcohol), carbon dioxide gas and a number of the corresponding by-products, as a function of yeast strain and conditions. The conventional fermentation is carried out together with the grape skins or with minimal contact with them, depending on the type of wine. Depending on the grape variety and wine style, fermentation is done in oak barrels or inert vessels or in a combination of the two. The yeast flocculates and dies off when most of the grape sugars are exhausted. The wine then undergoes further processing, such as aging, fining, flavor modification, blending, cold stabilization, filtration and bottling.
Numerous variations on the above procedures exist. Grapes may be mixed or substituted with other berries, fruits or sugar-containing plant material. Yeast fermentation may be accompanied and/or followed by malolactic fermentation, in which malic acid is converted by lactic acid bacteria to a softer-tasting lactic acid. The addition of K2S2O5 and pectolitic enzymes before fermentation improves color intensity and stability and increases content of total phenolics, including anthocyanins, (+)-catechin, (−)-epicatechin, rutin, and other flavonoids (Gambuti et al., 2007). Another of the procedure variations is microoxygenation, which is the controlled addition of small quantities of oxygen during the alcoholic fermentation, at the end of the primary fermentation or before malolactic fermentation. Once the treatment is finished, wine can be aged.
While some wines are bottled directly, other wines are aged in oak barrels prior to bottling, which adds an extra quality to the wine. The aging usually takes place in either oak barrels or vessels made of stainless steel or other inert material having no influence on wine taste. During the traditional aging process, wine is kept under an airlock to prevent oxidation. Unoaked wine can be briefly put in an oak barrel, or oak chips can be added. This type of aging is common in the production of less expensive wine.
Traditional oak barrel-aging is simple, but time-consuming. Peak flavor and bouquet require years to achieve and rapidly worsen thereafter. The processes taking place during wine aging are complex and very slow and include colloidal interactions between tannins, anthocyanins and their derivatives and proteins, which are broken down, and the remaining yeast, fine colloidal particles and potassium bitartrate precipitate. The initially cloudy liquid becomes clear. Aging in oak barrels is known to increase total phenolics and stabilizes wine color, but may lower the levels of anthocyanins, (+)-catechin, (−)-epticatechin, trans-resveratrol, and quercetin (Gambuti et al., 2007).
Color and taste changes during the aging of red wine are due to the reactions of the phenolic compounds that undergo numerous enzymatic and chemical reactions, such compounds being very unstable. Grape phenolics, which are responsible for the sensory properties of wine as well as the properties beneficial to human health, are very diverse in structure, ranging from simple molecules to oligomers and polymers designated as tannins, due to their ability to interact with proteins. The sensory properties of tannins and anthocyanins depend on their solubility and are affected by interactions with other wine components. The anthocyanin reactions generate colorless species and polymeric pigments that undergo sulfite bleaching while pigments with the lower molecular weight do not. The astringency loss during aging may be a result of cleavage rather than polymerization (Singleton, 1995; Poncet-Legrand et al., 2006; Cheynier et al., 2006).
In industrial aging, to imitate barrel-aging and enhance the extraction of vanillin, guaiacol and wood notes with fruity and varietal aromas the microoxygenation is commonly used in combination with oak chips (Heras et al., 2008). An alternative technology for aging red wines is electrochemical microoxidation, which is based on the precise control of the oxidation rate and treatment cut-off (Fell et al., 2007).
In practice, it is common to age wine in contact with the dead yeast cells (lees). The lees substantially affect the redox potential of the wine, making it more resistant to oxidation. Wine aged in the presence of lees is characterized by a rich nutty aroma, better creaminess and richness of mouth feel. White wine on lees is known to pick up oak notes less vigorously and integrates them into the bouquet more readily.
The aging is affected in many different ways by wine composition and the added ingredients that vary between wines and winemakers. When the wine peak has been achieved, the wine exhibits stable flavor and bouquet, being at its most preferred state for consumption. There are no precise criteria other than a subjective taste sensation and aroma that are both employed to determine whether the aging is complete and when the wine starts to decline. Following the peak period the process of decline from peak or deterioration begins, resulting in a loss of qualitative wine properties.
Prior to bottling, sulfur dioxide, sodium bisulfite, potassium bisulfite, ascorbic acid and/or other preservatives, antioxidants and food additives are introduced in almost all commercial wines to prevent oxidation, preserve flavor, and protect the color. The oxidized wine is often orange or brown, and has a distinctive taste of raisins.
During traditional oak barrel-aging, wine ingredients react very slowly with each other and the compounds extracted from the oak wood and the environment. Only low-energy reactions are feasible. Formation and/or disruption of bonds or changes in molecular structures and other chemical and physical conversions are not necessarily achieved, as these processes require more energy in order to proceed.
It has been reported that elevated pressure and increased temperature supplied by sound wave cavitation (Suslick, 1989) may accelerate aging of alcoholic beverages (Singleton and Draper, 1963). While extreme pressure or tremendous heat can be disadvantageous, the outcome of controlled treatment is highly beneficial. One approach illustrated in U.S. Pat. No. 2,086,891 to Bachmann et al. uses supersonic waves to produce a change in fermented and distilled beverages corresponding to the changes achieved via conventional aging. The treatment with the supersonic waves improves color, taste and bouquet in hours rather than the years required for a similar result through conventional aging.
Another approach is described in Japanese Patent No. 356068385 to Sakai who accelerated maturation of alcoholic beverages, such as brandy, liquor, sake, whisky or wine with the 16-60 kHz ultrasonic irradiation. The treatment is thought to promote chemical reactions of alcohols, aldehydes, esters and alkenes, such as condensation, oxidation, polymerization, and others. The treatment results in formation of new compounds with testable difference and a pleasant flavor and body.
Similarly, U.S. Patent Application Publication No. 2003/0110951 to Tyler, III et al. discloses a process for maturation of alcoholic beverages by subjecting them to ultrasound with a power of at least 5 W/L at 70-150° F. The product is superior in flavor in comparison to beverages aged by the traditional methods.
Australian Patent Application No. 2004284952 (WO/2005/042178) to Lee et al. relates to an apparatus and method for the treatment of wine using ultrasonic technology, and in particular to the introduction of a transducer of an ultrasonic processor into a wine-carrying or wine-storage container to induce ultrasonic cavitation within said wine and to thereby remove unwanted contaminates such as deposits, tartrates and residual yeasts or bacteria.
U.S. Pat. No. 7,220,439 to Leonhardt et al. describes altering the interactions of wine ingredients via application of ultrasonic radiation to a wine at a frequency causing cavitation, including when ultrasonic radiation is applied at two or more frequencies in a resonant frequency range of approximately 40-80 kHz and the two or more frequencies are applied in a sweeping manner.
Yet another U.S. Pat. No. 5,173,318 to Leu et al. describes a method of quickly aging distilled liquor that includes introducing ozone in the cooled beverage and applying an ultrasonic vibration at a frequency of 15-150 KHz to vibrate and heat the fermented product up to about 35° C. for oxidizing the fermented product.
U.S. Pat. No. 4,210,676 to Dudar et al. discloses a process for acceleration of the ripening of spirits through ultrasonic irradiation of the spirits in the presence of bouquet-improving additives, preferably wood, with an ultrasonic frequency of between 20-50 kHz and an output of about 1.7 W/L. During exposure to the ultrasonic irradiation, the alcoholic spirit is circulated through a closed system at a rate of 3-4 cycles per hour.
Effort has been undertaken to mature alcoholic beverages at frequencies below the ultrasonic range. U.S. Pat. Nos. 2,088,585 and 2,196,193 to Chambers et al. describe maturation of alcoholic beverages with sound waves, preferably in the sonic range. Although the low frequencies do create cavitation sufficient to accelerate the aging processes, the reaction products are not stable.
These and other prior patents (see, for example, U.S. Pat. No. 7,198,809 (Leonhardt et al.) and U.S. Patent Application No. 20060165855 (Leonhardt et al.) demonstrate that sound wave technology produces both pressure vibrations and cavitation that facilitate interaction of wine ingredients and extraction of wood notes in a batch environment. However, the technology could not be efficiently used in a continuous flow process because the energy density would be low and the residence time would be insufficient for the high speed production.
The prior art methods suffer from a number of other drawbacks. Since the effect of sonic cavitation diminishes with an increase in distance from the radiation source the treatment efficiency depends on container size and is low with large containers. Second, changes in fluid take place at particular locations, depending on the frequency of the radiation, i.e. its wavelength, and are not uniform throughout the volume. Thus, the efficacy of the treatment with sonic irradiation is further reduced.
The prior art techniques do not offer the most efficient method of producing a consumable beverage with an extended peak period of taste in the shortest amount of time possible. While previous uses of cavitation induced by sound waves in the acoustic range (20 Hz-20 KHz) and in the ultrasonic range (>20 KHz) claim to expedite aging of alcoholic beverages, they do no offer an optimized method for producing beverages. At the present time, with the cost of energy rising rapidly, it is highly desirable to shorten time and lower energy consumption to secure as large a profit margin as possible.
A need, therefore, exists for an advanced method and a flow-through system of beverage treatment and wine aging, with a minimal treatment time and energy cost, resulting in a product with an extended period of supreme taste, body and bouquet. The inventive method is particularly desired at harvest time, when throughput is a key demand. The present invention provides such a method and system while producing high quality beverages with superior taste, flavor, appearance, shelf life and stability made with the much faster treatment.
Hydrodynamic cavitation is the formation of gas bubbles in any turbulent fluid due to mechanically induced fluctuations in pressure. When a fluid is forced through a configuration that induces eddy currents, such as flow around surfaces or small and large cross-sectional areas in the flow stream, the fluid's velocity elevates at the expense of a drop in its pressure, causing dissolved or trapped gases and fluid vapor, i.e., volatile components, to form bubbles with a diameter from approximately 0.1 μm to a few millimeters in size. Small particulates and impurities serve as the nuclei for the bubbles. Once bubbles move from the region of the low pressure to the high pressure zone they will implode. The collapse releases a significant amount of energy in the form of shock waves, vigorous shearing forces and localized heating, all of which dissipate into the surrounding fluid. In some cases the collapse is accompanied by the formation of free radicals and the emission of UV and visible light. At the point of total collapse, the temperature and the pressure of the bubble vapors undergo temperature and pressure increases, sometimes as great as 5,000° C. and 1,000 atmospheres. (Suslick, 1989; Young 1999).
The phenomenon of cavitation is categorized by the dimensionless cavitation number Cv=(P∞−Pv)/0.5ρV∞2, where Pv is the vapor pressure, ρ is the liquid density, and P∞ and V∞ are the flow pressure and velocity, respectively (Passandideh-Fard and Roohi, 2008). It is known that a flow-through hydrodynamic cavitation can be created in fluid by means of various devices. See, for example, U.S. Pat. No. 7,207,712 (Kozyuk), U.S. Pat. No. 6,705,396 (Ivannikov et al.), U.S. Pat. No. 6,502,979 (Kozyuk), and U.S. Pat. No. 5,971,601 (Kozyuk), which describe a number of hydrodynamic cavitation devices and their uses.
U.S. Pat. No. 7,338,551 to Kozyuk discloses a device and method for generating microbubbles in a fluid that passes through a first local constriction of a hydrodynamic cavitation device at a velocity of at least 12 m/sec and then mixed with a gas to enhance implosion.
According to the invention of U.S. Pat. No. 6,227,694 to Mitake et al. a reaction between two or more reactive substances is generated through the collision of a jet flow of one reactive substance against a jet flow of another reactive substance at flow velocities of 4 m/sec or higher followed by furious turbulence and cavitation. The substances are flowed from different inflow passages and collided against each other at high flow rates to cause a uniform reaction within a short time. This method is advantageous for producing a dispersion containing very fine particles of submicron size.
There are many techniques for sterilization of liquid. Heating, autoclaving, treatment with antibiotics, disinfection with chlorine, ozone, permanganate and other reagents, filtration, sorption, ultraviolet and X-ray irradiation all remove pathogens. However, these techniques have disadvantages and limitations, such as insufficient efficacy, high cost, formation of unwanted by-products, risk associated with the use of hazardous compounds and harmful irradiation, and other limitations.
Cavitation in a fluid stream has found some application in controlling fluid quality. U.S. Pat. No. 6,200,486 to Chahine et al. discloses an approach utilizing cavitation occurring in shear zones associated with a jet nozzle to efficiently reduce contaminants in large volumes of liquid. The intense jet-induced cavitation triggers oxidation and reduction reactions, which cause decomposition and physical destruction of contaminants and microorganisms.
U.S. Pat. No. 7,247,244 to Kozyuk describes processes and devices for lowering the content of organic substances in fluids with the help of oxidizing agents that may be introduced into a local flow constriction in a flow-through chamber. Implosion of the cavitation bubbles, which contain and/or are associated with the oxidizing reagents, can be accompanied by the emission of ultraviolet (UV) light, ionization of the agents, generation of hydroxyl radicals, and decomposition and/or oxidation of the organic matter.
It should be emphasized that the UV-induced reactions and inactivation of microorganisms in fluids are strongly dependent upon the uniform exposure of the target species. Due to the shading effect of suspended particulate most of the current UV-based methods of both water and food sterilization exhibit limited potency.
Uniform exposure and mass transfer to the UV-irradiated surface can be achieved in an ultraviolet shockwave power reactor (UV-SPR) equipped with an inner rotating cylinder with surface cavities surrounded by a stationary quartz housing. The device allows for a UV dose increasing from 97 J/m2 at 0 rpm to 742 J/m2 for speeds above 2,400 rpm (Milly et al., 2007a). Inactivation of E. coli ATCC 25922 in apple juice and skim milk in the UV-SPR is greater by 4.5 and 3.0 logs, respectively. Although the rotor hydrodynamic cavitation inactivates various bacteria, yeast, yeast ascospores, and heat-resistant bacterial spores, system modification are needed to achieve commercial sterility in high-acid foods (Milly et al., 2007b). Lethality from the rotor hydrodynamic cavitation is known to be strongly dependent on the speed of the rotor. Processing temperatures and product exit temperature increase with maximal SPR residence time. Acidic fruit juices, salad dressings, and milk can be safely processed at reduced processing temperatures. Elevated temperature of the fluid fed in the reactor is an option to improve lethality at the relatively low pump pressure.
In addition, U.S. Patent Application No. 20050136123 to Kozyuk discloses a method for heat treating a homogenized fluid product, such as food, beverage, pharmaceutical, biotechnology, semiconductor, paint, ink, toner, fuel, magnetic media, or cosmetic industries' product, comprising feeding a stream of fluid product ingredients under pressure through a local flow constriction to induce high shear mixing of ingredients in a high shear mixing zone downstream from the constriction and forming a homogenized product at a first temperature; introducing a sufficient amount of the homogenized fluid product at a second temperature, which is less than the first temperature, into the high shear mixing zone to effectuate mixing of the homogenized fluid product at the first temperature with the homogenized fluid product at the second temperature to thereby heat treat the homogenized fluid product.